Monumental arch erected to commemorate national events, especially military victories. Triumphal arches were first used in ancient Rome, the term originally applying to an arch erected to commemorate a formal ‘triumph’ awarded at Rome to a victorious general, who led his army in procession through the Porta Triumphalis in a chariot drawn by white horses. While many such arches exist, the term is more loosely applied to other commemorative arches, which the Romans erected to mark the founding of colonies, the building of roads and bridges, the death of a member of the imperial family or the accession of a new emperor, and these became potent symbols of Roman Imperial power throughout the Empire. The arches of aqueducts at the point where they crossed an important road were sometimes decorated as if they were triumphal arches, as were important city gates. Commemorative arches have either a single or a triple opening, or can be placed over a crossroads with arched openings on all four sides. The one-bay arch is the most widespread, and examples range from the very simple type with an opening flanked by pilasters to massive arches with elaborate sculptural decoration. The triple type has a large central aperture over the roadway flanked by lesser openings over the pavements. A commemorative arch usually stands in isolation and has no practical function but is splendidly decorated....